BS EN 60079-6:2015 BSI Standards Publication Explosive atmospheres Part 6: Equipment protection by liquid immersion “o” BRITISH STANDARD BS EN 60079-6:2015 National foreword This British Standard is the UK implementation of EN 60079-6:2015 It is identical to IEC 60079-6:2015 It supersedes BS EN 60079-6:2007 which is withdrawn The UK participation in its preparation was entrusted to Technical Committee EXL/31, Equipment for explosive atmospheres A list of organizations represented on this committee can be obtained on request to its secretary This publication does not purport to include all the necessary provisions of a contract Users are responsible for its correct application © The British Standards Institution 2015 Published by BSI Standards Limited 2015 ISBN 978 580 79836 ICS 29.260.20 Compliance with a British Standard cannot confer immunity from legal obligations This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 December 2015 Amendments/corrigenda issued since publication Date Text affected BS EN 60079-6:2015 EUROPEAN STANDARD EN 60079-6 NORME EUROPÉENNE EUROPÄISCHE NORM December 2015 ICS 29.260.20 Supersedes EN 60079-6:2007 English Version Explosive atmospheres - Part 6: Equipment protection by liquid immersion "o" (IEC 60079-6:2015) Atmosphères explosives - Partie 6: Protection du matériel par immersion dans le liquide "o" (IEC 60079-6:2015) Explosionsgefährdete Bereiche - Teil 6: Geräteschutz durch Flüssigkeitskapselung "o" (IEC 60079-6:2015) This European Standard was approved by CENELEC on 2015-03-27 CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CENELEC member This European Standard exists in three official versions (English, French, German) A version in any other language made by translation under the responsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the same status as the official versions CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom European Committee for Electrotechnical Standardization Comité Européen de Normalisation Electrotechnique Europäisches Komitee für Elektrotechnische Normung CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels © 2015 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members Ref No EN 60079-6:2015 E BS EN 60079-6:2015 EN 60079-6:2015 (E) European foreword The text of document 31/1157/FDIS, future edition of IEC 60079-6, prepared by IEC/TC 31 "Equipment for explosive atmospheres" was submitted to the IEC-CENELEC parallel vote and approved by CENELEC as EN 60079-6:2015 The following dates are fixed: • • latest date by which the document has to be implemented at national level by publication of an identical national standard or by endorsement latest date by which the national standards conflicting with the document have to be withdrawn (dop) 2016-06-11 (dow) 2018-03-27 This document supersedes EN 60079-6:2007 Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights CENELEC [and/or CEN] shall not be held responsible for identifying any or all such patent rights This document has been prepared under a mandate given to CENELEC by the European Commission and the European Free Trade Association, and supports essential requirements of EU Directive(s) For the relationship with EU Directive(s) see informative Annex ZZ, which is an integral part of this document Endorsement notice The text of the International Standard IEC 60079-6:2015 was approved by CENELEC as a European Standard without any modification In the official version, for Bibliography, the following notes have to be added for the standards indicated: IEC 60079 series NOTE Harmonized in the series EN 60079 IEC 62770 NOTE Harmonized as EN 62770 BS EN 60079-6:2015 EN 60079-6:2015 (E) Annex ZA (normative) Normative references to international publications with their corresponding European publications The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application For dated references, only the edition cited applies For undated references, the latest edition of the referenced document (including any amendments) applies NOTE When an International Publication has been modified by common modifications, indicated by (mod), the relevant EN/HD applies NOTE Up-to-date information on the latest versions of the European Standards listed in this annex is available here: www.cenelec.eu Publication IEC 60079-0 Year - IEC 60156 - IEC 60247 - IEC 60296 - IEC 60529 - IEC 60814 - IEC 60836 - IEC 61099 - IEC 61125 IEC 62021-1 - IEC 62535 - ISO 2592 - ISO 2719 - ISO 3016 - Title EN/HD Explosive atmospheres Part 0: EN 60079-0 Equipment - General requirements Insulating liquids - Determination of the EN 60156 breakdown voltage at power frequency Test method Insulating liquids - Measurement of relative EN 60247 permittivity, dielectric dissipation factor (tan d) and d.c resistivity Fluids for electrotechnical applications EN 60296 Unused mineral insulating oils for transformers and switchgear Degrees of protection provided by enclosures (IP Code) Insulating liquids - Oil-impregnated paper EN 60814 and pressboard - Determination of water by automatic coulometric Karl Fischer titration Specifications for unused silicone EN 60836 insulating liquids for electrotechnical purposes Insulating liquids - Specifications for EN 61099 unused synthetic organic esters for electrical purposes EN 61125 Insulating liquids - Determination of acidity EN 62021-1 Part 1: Automatic potentiometric titration Insulating liquids - Test method for EN 62535 detection of potentially corrosive sulphur in used and unused insulating oil Determination of flash and fire points EN ISO 2592 Cleveland open cup method Determination of flash point - PenskyEN ISO 2719 Martens closed cup method Petroleum products - Determination of pour point Year - BS EN 60079-6:2015 EN 60079-6:2015 (E) ISO 3104 - Petroleum products - Transparent and opaque liquids - Determination of kinematic viscosity and calculation of dynamic viscosity EN ISO 3104 - BS EN 60079-6:2015 EN 60079-6:2015 (E) Annex ZZ (informative) Relationship between this European standard and the essential requirements of Directive 94/9/EC aimed to be covered This European standard has been prepared under a Commission’s standardisation request to provide one voluntary means of conforming to essential of Directive 94/9/EC of the European Parliament and the Council of 23 March 1994 on the approximation of the laws of the Member States concerning equipment and protective systems intended for use in potentially explosive atmospheres Once this standard is cited in the Official Journal of the European Union under that Directive, compliance with the normative clauses of this standard given in Table ZZ.1 confers, within the limits of the scope of this standard, a presumption of conformity with the corresponding essential requirements of that Directive, and associated EFTA regulations Table ZZ.1 – Correspondence between this European standard and Annex II of Directive 94/9/EC Essential Requirements of Directive 1.0.1 Clause(s) / sub-clause(s) of this EN 4, 1.0.2 1.0.3 7, 1.0.4 Not covered 1.0.5 1.0.6 1.1.1 4, 1.1.2 4, 1.1.3 1.2.1 4, 1.2.2 1.2.3 Not covered 1.2.4 1.2.5 Not covered 1.2.6 4.5 1.2.7 Not covered 1.2.8 Not covered Remarks / Notes BS EN 60079-6:2015 EN 60079-6:2015 (E) 1.2.9 Not covered 1.3.1 All 1.3.2 4.5 1.3.3 Not covered 1.3.4 Not covered 1.3.5 Not covered 1.4.1 1.4.2 1.5.1 4.5, 4.6, 4.7 1.5.2 Not covered 1.5.3 Not covered 1.5.4 4.6, 4.7 1.5.5 4.6, 4.7 1.5.6 Not covered 1.5.7 Not covered 1.5.8 Not covered 1.6.1 Not covered 1.6.2 Not covered 1.6.3 Not covered 1.6.4 4.9 1.6.5 Not covered 2.0.1.1 4, 2.0.1.2 4.5 2.0.1.3 4.8 2.0.1.4 Not covered 2.0.2.1 4.1, 4.8 2.0.2.2 4.5 Covered by the principle of the type of protection "o": Immersion of potential ignition sources in oil BS EN 60079-6:2015 EN 60079-6:2015 (E) 2.0.2.3 4.5 2.1.1.1 4, 2.1.1.2 4.8 2.1.1.3 4.5 2.1.2.1 4, 2.1.2.2 Not covered 2.1.2.3 Not covered 2.2.1.1 4.1, 4.2.2, 4.5 2.2.1.2 4.8 2.2.1.3 4.5 2.2.2.1 4.1, 4.2.2, 4.5 2.2.2.2 Not covered 2.2.2.3 Not covered 2.2.2.4 Not covered 2.3.1.1 4.1, 4.2.3, 4.5 2.3.1.2 4.8 2.3.2.1 4.1, 4.2.3, 4.5 2.3.2.2 4.8 2.3.2.3 Not covered 3.0.1 Not covered 3.0.2 Not covered 3.0.3 Not covered 3.0.4 Not covered 3.1.1 Not covered 3.1.2 Not covered 3.1.3 Not covered 3.1.4 Not covered 3.1.5 Not covered and and BS EN 60079-6:2015 EN 60079-6:2015 (E) 3.1.6 Not covered 3.1.7 Not covered 3.1.8 Not covered WARNING 1: Presumption of conformity stays valid only as long as a reference to this European standard is maintained in the list published in the Official Journal of the European Union Users of this standard should consult frequently the latest list published in the Official Journal of the European Union WARNING 2: Other Union legislation may be applicable to the product falling within the scope of this standard BS EN 60079-6:2015 IEC 60079-6:2015 © IEC 2015 –9– b) Level of Protection “oc” (EPL Gc) The requirements of this standard shall apply to all levels of protection unless otherwise stated 4.2.2 Requirements for Level of Protection “ob” Electrical circuits and components, when liquid immersed in accordance with this standard, are considered to be not ignition capable in normal operation and during expected malfunctions, and shall be assigned a Level of Protection “ob” (EPL Gb or Mb) A liquid level indication according to 4.7 is required Switching devices protected by liquid immersion level of protection “ob” shall comply with the following additional requirements: a) When a sealed enclosure is employed, the enclosure shall comply with the overpressure test in 6.1.1 using four times the prescribed pressure b) Electrical equipment containing switching devices operated in the protective liquid, rated at kVA per contact or less, are permitted without further test Where the switching device is rated above kVA per contact, neither pressure increases nor excessive decomposition products shall invalidate the type of protection as demonstrated by tests in accordance with 6.1.5 c) The equipment shall be suitable for a prospective short circuit current of 32 kA unless marked with a lower value Disconnectors and manual tap selectors, above 000 V, shall be lockable and provided with a warning according to i) In addition, information on their use shall be included in the instructions 4.2.3 Requirements for Level of Protection “oc” Electrical circuits and components, when liquid immersed in accordance with this standard, are considered to be not ignition capable in normal operation or in the case of regular expected occurrences, and shall be assigned a Level of Protection “oc” (EPL Gc) Ex Equipment containing switching devices operated in the protective liquid, rated at 10 kVA per contact or less, are permitted without further test For switching devices rated above 10 kVA per contact, neither pressure increases nor excessive decomposition products shall invalidate the type of protection as demonstrated by tests in accordance with 6.1.5 4.3 Switching device Switching devices are only permitted for a.c circuits where the working voltage of the switch does not exceed the values given in Table Switching devices for d.c circuits are not permitted Table – Working voltage 4.4 Level of Protection “ob” “oc” Working voltage of switching device 000 V r.m.s a.c 6,6 kV r.m.s a.c Creepage and clearance Electrical circuits and components intended to be immersed in the protective liquid shall meet the relevant industrial requirements for creepage and clearance distances in air before being immersed in the protective liquid If the relevant industrial standard gives options for pollution degree, pollution degree shall be assumed – 10 – 4.5 4.5.1 BS EN 60079-6:2015 IEC 60079-6:2015 © IEC 2015 Liquid containment enclosures General The chemical resistance against the protective liquid shall be documented by the manufacturer NOTE It is not a requirement of this standard that conformity to the chemical resistance against the protective liquid be verified The enclosures shall be subjected to the type tests as specified in Clause for sealed and unsealed enclosures respectively Connection bushings provided for termination of the electrical conductors shall be considered as part of the enclosure and subject to the requirements of this clause 4.5.2 Sealed enclosures Covers of sealed enclosures may be continuously welded to the enclosure, or sealed by means of a gasket, in which case, the cover shall be provided with special fasteners according to IEC 60079-0 Equipment with a sealed enclosure shall be provided with a pressure-relief device This device shall be permanently set by the manufacturer of the liquid-filled equipment to operate at a pressure of at least 10 kPa Enclosures permanently sealed at the time of manufacture shall not be capable of being opened without leaving visible evidence that the enclosure has been opened The enclosure shall be marked in accordance with c) NOTE Suitable techniques that can provide visible evidence of being opened are, for example, welding, soldering, cemented joints, rivets, cementing of screws, or lead-seal safety-wiring of screws 4.5.3 Unsealed enclosures An enclosure, which is not sealed, shall be constructed so that gas or vapour that may evolve from the protective liquid in normal service can escape through a breathing device which includes a suitable drying agent The manufacturer shall specify the maintenance requirements for the drying agent 4.5.4 Outlet of breathing device or pressure relief device The outlet of the breathing device for unsealed equipment and the outlet of the pressure relief device for sealed equipment shall face down and have a degree of protection of at least IP66 as given in IEC 60529 4.5.5 Enclosures intended to be opened Enclosure that are designed to be opened shall incorporate sealing methods that are capable of being renewed without damage to the enclosure when the equipment is repaired, refilled and resealed The enclosure shall be marked in accordance with d) 4.5.6 Determination of the maximum/minimum criteria of the protective liquid The following criteria shall be specified: a) the maximum and minimum level of the protective liquid; b) the maximum working angle, from the horizontal, of the equipment; BS EN 60079-6:2015 IEC 60079-6:2015 © IEC 2015 4.6 – 11 – Immersion depth Live parts of the electrical equipment shall be immersed to a depth according to Table within the protective liquid, at the minimum possible liquid level no matter the orientation of the internal equipment Table – Depth of immersion a Voltage (See a ) U r.m.s a.c or d.c V No switching device With a switching device (a.c only) ≤ 50 V mm 10 mm ≤ 250 V mm 15 mm ≤ 000 V 10 mm 20 mm ≤ 000 V 25 mm 50 mm ≤ 10 000 V 25 mm – ≤ 13 640 V 50 mm – Distance When determining the required values for depth of immersion, the working voltage may be higher than the voltage in the table by a factor of 1,1 (see Note) NOTE The factor of 1,1 recognizes that at many places in a circuit, the working voltage equals the rated voltage and that there are a number of rated voltages in common use that can be accommodated by the 1,1 factor 4.7 4.7.1 Protective liquid level indication General Protective liquid level indicating device(s) complying with the following requirements shall be provided so that the liquid level of each separate liquid-filled compartment can be easily checked in service The maximum and the minimum protective liquid levels permissible in normal service shall be marked in accordance with e), taking into account the effects of expansion and contraction resulting from operational temperature changes over the full ambient temperature range specified by the manufacturer The protective liquid level indicating device shall be marked in accordance with f) to indicate the levels to which the electrical equipment shall be filled under the filling temperature conditions specified by the manufacturer Alternatively, an adjacent label shall be provided which fully specifies the filling conditions The location of the protective liquid level indicating device shall be such that the minimum possible indicated level of the protective liquid cannot be beneath the level necessary to comply with 4.6, taking into account the effects of expansion and contraction resulting from operational temperature changes over the full ambient temperature range specified by the manufacturer The manufacturer shall prepare documentation to show that transparent parts will retain their mechanical and optical properties when in contact with the protective liquid For non-sealed equipment, a dipstick may be used provided that, in normal operation, the dipstick is secured in its measurement position and that the requirements of 4.5.1 with regard to ingress protection are maintained An adjacent warning marking shall be provided in accordance with g) – 12 – 4.7.2 BS EN 60079-6:2015 IEC 60079-6:2015 © IEC 2015 Remote-indicating protective liquid level indicator If a remote-indicating protective liquid level indicator is provided, the switching element shall be lower than the sensing element by at least the dimension shown in Table 2, or it shall be protected by one of the types of protection suitable for the application If the manufacturer does not provide the remote-indicating liquid level indicator, the certificate number shall include the "X" suffix in accordance with IEC 60079-0 and the Specific Condition of Use shall specify all necessary information required by the user to ensure conformity with the requirements of this standard 4.7.3 Safety devices for Level of Protection “ob” For Level of Protection “ob” with switching devices, a protective liquid level safety device shall monitor the level of the protective liquid and provide for automatic disconnection of power upon reduction of oil below the permitted minimum The switching element of the safety device shall be lower than the sensing element of the safety device by at least the dimension shown in Table 2, or shall be protected by one of the types of protection suitable for the application If the manufacturer does not provide the safety devices, the certificate number shall include the "X" suffix in accordance with IEC 60079-0 and the Specific Condition of Use shall specify all necessary information required by the user to ensure conformity with the requirements of this standard NOTE Safety devices for these applications normally have a fault tolerance of and a safety integrity level SIL Requirements for such safety devices are currently given in EN 50495 A project has been initiated to consider the development of an IEC standard based on EN 50495 which would provide requirements for these safety devices 4.8 4.8.1 Temperature limitations General The maximum permissible temperature for equipment or parts of equipment shall be equal to the lower of the two temperatures determined by 4.8.2 or 4.8.3 4.8.2 Maximum Surface Temperature The temperature at the free surface of the protective liquid or at any point on the surface of the electrical equipment to which an explosive gas atmosphere has access shall not exceed the limit for the assigned temperature class or assigned maximum surface temperature In no case shall the limit exceed 200 °C 4.8.3 Flashpoint of the protective liquid The stated minimum flash-point (closed cup) for the protective liquid used shall be at least 25 K greater than the temperature at the free surface of the protective liquid and the temperature of the internal components immersed in the liquid 4.9 Field wiring connections to liquid immersion equipment Liquid immersion is not an accepted type of protection for field wiring connections Bushings shall be used for connections through the wall of the equipment Direct entry is not permitted The field wiring connections shall be protected with a type of protection suitable for the application 4.10 4.10.1 Constructional elements of enclosures Operating rods, shafts etc If the enclosure contains operating rods, shafts etc it shall comply with the tests of 6.1.1 and 6.1.2 if a sealed enclosure and 6.1.3 if an unsealed enclosure The tests shall be carried out BS EN 60079-6:2015 IEC 60079-6:2015 © IEC 2015 – 13 – with such elements in place Operating rods or shafts used in a sealed enclosure shall be subject to a conditioning of 500 operations prior to the tests of 6.1.1 and 6.1.2 4.10.2 Devices for draining of liquid Devices for draining the liquid shall be secured against inadvertent removal 5.1 Protective Liquid Protective liquid specification The protective liquid shall be a mineral oil conforming to IEC 60296, a silicone liquid conforming to IEC 60836, a synthetic organic ester liquid (Type T1) conforming to IEC 61099, or shall be a liquid conforming to the requirements of 5.2 NOTE The future use of natural ester liquids per IEC 62770 is under consideration 5.2 Detailed alternative specification The specification for the alternative protective liquid shall include the following: a) the protective liquid shall have a fire point of not less than 300 °C determined by the test method indicated in ISO 2592; b) the protective liquid flash-point (closed cup) determined in accordance with ISO 2719 shall be not less than 25 K above the free surface temperature of the protective liquid (See 4.8.3); c) the protective liquid shall have a kinematic viscosity of not more than 100 cSt at 25 °C determined in accordance with ISO 3104; d) the protective liquid shall have an electrical breakdown strength of not less than 30 kV determined in accordance with IEC 60156; e) the protective liquid shall have a volume resistivity at 25 °C of not less than × 10 12 Ω × m determined in accordance with IEC 60247; f) the pour point, determined in accordance with ISO 3016, shall be no higher than the lower of -30 °C or 10 K less than the minimum ambient temperature of the equipment; g) the acidity (neutralization value) shall be not more than 0,03 mg KOH/g determined in accordance with IEC 62021-1; h) the protective liquid shall have no adverse effect on the properties of materials with which it is in contact; i) the oxidation stability shall not exceed 0,15 % sludge according to IEC 61125; j) the sulphur content shall be confirmed as non-corrosive according to IEC 62535; and k) the water content shall not exceed 35 ppm according to IEC 60814 NOTE It is not a requirement of this standard that conformity to the specification of the protective liquid be verified 5.3 Group I equipment For Group I equipment, mineral oils are not acceptable 5.4 Liquid contamination and gassing that may result from arcing Where switching devices are incorporated in the electrical equipment and may give rise to contamination of the protective liquid, suitable maintenance instructions shall be prepared As a minimum these will include instructions for the cleaning/filtering/replacement of the protective liquid following a given number of normal switching operations and following interruption of fault currents – 14 – 5.5 BS EN 60079-6:2015 IEC 60079-6:2015 © IEC 2015 Total volume of the protective liquid The documentation prepared in accordance with IEC 60079-0 shall specify the total volume of the protective liquid, including the maximum and minimum volumes to maintain the levels required as given in 4.6 Verifications and tests 6.1 6.1.1 Type tests Overpressure test on sealed enclosures For Level of Protection “ob” with a switching device switching more than kVA per contact, a pressure equal to times the pressure relief device setting, and for all other enclosures, a pressure equal to 1,5 times the pressure relief device setting shall be applied internally In no case shall the test pressure be less than 150 kPa The period of application of the pressure shall be at least 60 s The pressure relief device entry shall be sealed for the duration of the test The test shall be considered satisfactory if, at the end of the test, the enclosure has suffered neither damage nor permanent distortion which adversely affects its ability to comply with 4.6 NOTE A non-compressible hydraulic media is normally used for these tests If a compressible media such as air or inert gas is used, failure of the enclosure can result in personal injury or property damage 6.1.2 Reduced pressure test on sealed enclosures The internal pressure of the enclosure without protective liquid shall be reduced by an amount equivalent to not less than the pressure that would result from a change in the protective liquid level from the maximum permissible level to the minimum permissible level when appropriately corrected for any ambient temperature variations specified in the documentation At the end of 24 h, any increase in pressure shall not exceed % 6.1.3 Overpressure test on unsealed enclosures A pressure equal to 150 kPa, with the breather sealed, shall be applied internally The period of application shall be at least 60 s The test shall be considered satisfactory if, at the end of the test, the enclosure has suffered neither damage nor permanent distortion that adversely affects its ability to comply with 4.5.3 and 4.5.5 NOTE A non-compressible hydraulic media is normally used for these tests If a compressible media such as air or inert gas is used, failure of the enclosure can result in personal injury or property damage 6.1.4 Maximum temperature A sample of “o” equipment shall be subjected to a type test to ensure that the temperature limits specified in 4.8 are not exceeded For “o” equipment without an external load, the test shall be carried out in accordance with the temperature measurements of IEC 60079-0 For “o” equipment with an external load, the test shall be carried out for Level of Protection “ob” by adjusting the current to 110 % of the rated current and for Level of Protection “oc” at 100 % of the rated current in normal operation and at the maximum rated duty cycle BS EN 60079-6:2015 IEC 60079-6:2015 © IEC 2015 – 15 – NOTE Equipment with characteristics such as non-linear external loads, input power control or difficult to define failure modes introduces challenges into the determination of maximum temperatures under malfunction conditions 6.1.5 Switching Tests The electrical switching tests given in the relevant IEC industrial standards shall be carried out with the equipment in its design configuration The protective liquid shall be at minimum level At the conclusion of the tests: a) there shall be no release of the protective liquid nor shall the required creepage and clearance distances be compromised; and b) the protective liquid shall have an electrical breakdown strength of not less than 30 kV determined in accordance with IEC 60156 6.2 Routine tests 6.2.1 Sealed enclosures Each sealed enclosure shall be subjected to both the following tests in sequence: a) the overpressure test described in 6.1.1 This routine test may be omitted for other than welded enclosures, if during type testing, the equipment complies with the acceptance criteria in 6.1.1 using four times the pressure relief device setting; NOTE A non-compressible hydraulic media is normally used for these tests If a compressible media such as air or inert gas is used, failure of the enclosure can result in personal injury or property damage b) the test described in 6.1.2 or an equivalent accelerated test using a lower pressure In the latter case, the calculations shall be documented to demonstrate that his test will achieve the same threshold value of leakage as in the 24 h test 6.2.2 Unsealed enclosures Each unsealed enclosure shall be subjected to the test specified in 6.1.3 This routine test may be omitted for other than welded enclosures, if during type testing; the equipment complies with the acceptance criteria in 6.1.3 using 600 kPa NOTE A non-compressible hydraulic media is normally used for these tests If a compressible media such as air or inert gas is used, failure of the enclosure can result in personal injury or property damage Marking Ex Equipment or Ex Components of liquid immersion “o” shall be marked in accordance with IEC 60079-0, with the following additional marking: a) the protective liquid to be used; b) the pressure relief device setting (where appropriate); c) “This enclosure has been permanently sealed and cannot be repaired” (where appropriate); d) “This enclosure is factory sealed – Consult manufacturer’s instructions for repair” (where appropriate); e) minimum and maximum level of protective fluid; f) the levels to which the Ex Equipment shall be filled under the filling temperature conditions specified by the manufacturer Alternatively, an adjacent label shall be provided which fully specifies the filling conditions; g) when a dipstick is employed in accordance with 4.7.1, the marking “WARNING – Replace dipstick after use”, or technically equivalent text h) permitted prospective short-circuit current of the external electrical supply if the equipment is designed for a short-circuit current less than 32 kA, according to 4.2.2 c), for example “Permitted supply short-circuit current: 10 kA”; – 16 – i) BS EN 60079-6:2015 IEC 60079-6:2015 © IEC 2015 “WARNING – Operate only at NO LOAD” according to 4.2.2 The Ex Equipment or Ex Components shall be marked as “ob” (for EPL Gb or Mb) or “oc” (for EPL Gc), as appropriate, replacing the marking “o” (for EPL Gb) shown in IEC 60079-0 Instructions All liquid-immersed “o” Ex Equipment shall be accompanied by instructions as required by IEC 60079-0, including the following additional particulars as a minimum: a) Details on the frequency of replacement of the protective fluid including details on the specific protective fluid to be used b) Information on the use of disconnectors and tap selectors according to 4.2.2 c) The maintenance requirements for the drying agent for the breathing device for unsealed enclosures d) Instructions for the cleaning/filtering/replacement of the protective liquid following a given number of normal switching operations and following interruption of fault currents BS EN 60079-6:2015 IEC 60079-6:2015 © IEC 2015 – 17 – Annex A (normative) Selection and erection requirements Ex Equipment having type of protection “o” shall be installed in accordance with the following: • Level of Protection “ob” equipment may be installed in locations requiring equipment suitable for EPL “Mb” “Gb” or Gc • Level of Protection “oc” equipment may be installed in locations requiring equipment suitable for EPL Gc • The field wiring connections shall be protected with a type of protection suitable for the application • Liquid immersion is not an accepted Type of Protection for field wiring connections Direct entry is not permitted NOTE The selection and erection of the equipment requirements are found in IEC 60079-14 and are the responsibility of the user Until IEC 60079-14 contains sufficient information, this Annex A provides information – 18 – BS EN 60079-6:2015 IEC 60079-6:2015 © IEC 2015 Annex B (normative) Maintenance requirements The inspection requirements of IEC 60079-17 are supplemented by those shown in Table B.1 Table B.1 – Inspection requirements Check that: Grade of inspection D C V A EQUIPMENT Equipment is appropriate to the EPL/Zone requirements of the location X X X Equipment group is correct X X X Equipment temperature class is correct X X Equipment circuit identification is correct X X X Equipment circuit identification is available X X X Enclosure, glass parts and glass-to-metal sealing gaskets and/or compounds are satisfactory X X X There are no unauthorized modifications X X X There are no visible unauthorized modifications X X Bolts, cable entry devices (indirect) and blanking elements are of the correct type and are complete and tight X X X – physical check – visual check 10 Electrical connections are tight X X X 11 Condition of enclosure gaskets is satisfactory X X X 12 Breathing and draining devices are satisfactory The manufacturer’s schedule for maintenance X X X requirements for the drying agent are documented to have been followed 13 Sealed enclosure pressure-relief devices are satisfactory X X 14 Enclosures marked Permanently Sealed have no visible evidence that the enclosure has been opened X X X 15 maximum/minimum criteria of the protective liquid X X X X X X 16 a) level of the protective liquid shall be at or below the maximum and above the minimum permitted level; b) the maximum working angle to the horizontal of the equipment shall be satisfactory Enclosures intended to be opened The level of the protective liquid in Type of Protection “o” electrical equipment designed to be opened shall be re-filled to within the required level range with the protective liquid required and re-sealed in accordance with the manufacturer’s instructions 17 When a dipstick is provided, the dipstick is secured in its measurement position and its seal is satisfactory X X X 18 remote-indicating protective liquid level indicating device operation is satisfactory X X X 19 switching device schedule for cleaning/filtering/replacement of the protective liquid following a given number of normal switching operations or interruption of fault currents is documented X X X NOTE The inspection and maintenance requirements are found in IEC 60079-17 and are the responsibility of the user Until IEC 60079-17 contains sufficient information, Annex B provides information BS EN 60079-6:2015 IEC 60079-6:2015 © IEC 2015 – 19 – Annex C (normative) Repair and Overhaul requirements Repair, overhaul and reclamation is not applicable to Type of Protection “o” Ex Equipment with enclosures indicated as being sealed Type of Protection “o” enclosures that are intended to be opened shall be subject to repair, overhaul and reclamation only as permitted by the manufacturer’s instructions NOTE The repair and overhaul requirements are found in IEC 60079-19 and are the responsibility of the user Until IEC 60079-19 contains sufficient information, Annex C provides information – 20 – BS EN 60079-6:2015 IEC 60079-6:2015 © IEC 2015 Bibliography IEC 60050-421, International Electrotechnical Vocabulary – Chapter 421: Power transformers and reactors IEC 60050-441, International Electrotechnical Vocabulary – Chapter 441: Switchgear, controlgear and fuses IEC 60079 (all parts), Explosive atmospheres IEC 62770, Fluids for electrotechnical applications – Unused natural esters for transformers and similar electrical equipment EN 50495, Safety devices required for the safe functioning of equipment with respect to explosion risks _ This page deliberately left blank